Currently, there is a large effort to automate labor intensive operations and processes. For example, the operations performed by earthmoving or construction machines lend themselves to the benefits of automation. The machines perform many repetitive tasks which are usually performed by skilled operators. Also, automation of their operation would allow near continuous operation of the machines which would improve efficiency and productivity.
Automation of large earthmoving or construction machines is very complex and involves the solution of many problems. First, an accurate determination of the position of each machine must be made. Such determinations have been attempted through "dead-reckoning" systems, laser beam reference systems and satellite based systems.
Dead-reckoning systems use on-board odometers, speedometers, and/or other devices to measure the distance and direction a machine has traveled. Such systems are relatively simple and inexpensive, but are not as accurate as the other two systems.
Laser reference systems provide a laser reference, usually via a laser beam rotated in a plane. While tending to be more accurate then dead-reckoning systems, laser reference systems require each machine to be equipped with laser beam sensors. Additionally, the precise location of each laser emitter must be known. Thus, an emitter cannot be moved without determining the precise location of its new position. This limits the effective range and usefulness of laser reference systems.
In addition, particles in the surrounding air, for example, rain, snow, or dust, will obscure the laser beam and prevent the sensors form detecting the laser beam.
Furthermore, the laser beams have a limited range of, generally, less than 1 kilometer.
Satellite systems are based on signals received from earth-orbiting satellites. Each machine includes a receiver for receiving the signals transmitted by the satellites and utilizes triangulation methods for determining its position.
A second problem to be overcome in automating such systems is scheduling. Typically in a non-automated system, a dispatcher, located at a central location, tracks the locations of the machines in the system via radio communications with the drivers of each machine. The dispatcher also has a record of the work required to be accomplished at the site. The dispatcher then radios the operators to travel to locations within the site to perform specific work.
In an autonomous system, the human dispatcher is replaced with a computer based dispatcher or scheduler. The scheduler is located at a central location, the base station. Like the human dispatcher, the scheduler tracks the location of autonomous machines and the work needed to be done. Also, the scheduler commands the autonomous machines to travel to locations to perform specific work.
However, once the machines are situated at the specific work areas, if the work to be done requires cooperation between two or more machines, the control of each machine becomes more complex. For example, in a digging and loading operation performed by at least one loading machine and one or more hauling machines, the loading machine must travel a path from a digging position to a dumping position. Also, the control of the machines must take into account the local geography and obstacles. Further, the exact position of each machine becomes more critical because of the close proximity of the other machines. Therefore, it may be more desirable to provide more localized control and planning during operations requiring cooperation between two or more machines.
The present invention is directed to overcoming one or more of the problems, as set forth above.